Particulate bleaching compositions based on peroxygen oxygen bleaches suitable for the bleaching of stains on fabrics are based on so-called persalt bleaches such as sodium perborate, in its various hydrate forms, or on sodium percarbonate. Such persalt bleaches are sources of hydrogen peroxide when used in aqueous washing conditions. Nowadays, these compositions are very appreciated among consumers and there is a constant need to improve their performances. Particulate bleaching compositions contain thus more and more auxiliary ingredients, such as enzymes, which increase the performances of composition.
Cellulase enzymes have been used in detergent compositions for many years now for their known benefits of depilling, softness and colour care. However, the use of most of cellulases has been limited because of the negative impact that cellulase may have on the tensile strength of the fabrics' fibers by hydrolysing crystalline cellulose. Recently, cellulases with a high specificity towards amorphous cellulose have been developed to exploit the cleaning potential of cellulases while avoiding the negative tensile strength loss.
For example, Novozymes, in WO02/099091, discloses a novel enzyme exhibiting endo-beta-glucanase activity for use in detergent and textile applications. Novozymes further describes, in WO04/053039, detergent compositions comprising an endoglucanase and its combination with cellulases having increased stability towards anionic surfactant. Kao's EP 265832 describes novel alkaline cellulase. Kao further describes, in EP 1350843, alkaline cellulase which acts favourably in an alkaline environment.
However, it has always been difficult to formulate particulate bleach additive composition containing enzymes. It is, thus, an objective of the present invention to provide a particulate bleach additive composition comprising enzyme, which delivers effective bleaching performance on stained fabrics, when used in conjunction with a conventional particulate laundry detergent. The inventors have now found that the combination of some enzymes with particulate bleaching compositions, based on peroxygen oxygen bleaches, leads to a surprising improvement in cleaning and in whitening performance as well as on fabrics safety.
An advantage of the compositions of the present invention is, thus, that the particulate bleach additives herein are suitable for the bleaching of different types of fabrics including natural fabrics, (e.g., fabrics made of cotton, and linen), synthetic fabrics such as those made of polymeric fibres of synthetic origin (e.g., polyamide-elasthane) as well as those made of both natural and synthetic fibres. For example, the particulate bleach additives of the present invention herein may be used on synthetic fabrics despite a standing prejudice against using bleaches on synthetic fabrics, as evidenced by warnings on labels of clothes and commercially available bleaching compositions like hypochlorite-containing compositions. The compositions of the present invention have thus the benefit of having excellent cleaning performance while still being safe to fabrics.
Another advantage of the particulate bleach additives according to the present invention is that they can be used in a variety of conditions, i.e., in hard and soft water.
Yet another advantage of the compositions of the present invention is that they exhibit also effective stain removal performance on various stains including enzymatic stains and/or greasy stains.
By “bleach additives” it is meant herein, a particulate composition that is used in conjunction with, this means added to the washing machine together with, a conventional laundry detergent, in particular a particulate laundry detergent, in a laundry washing operation.